Generally, a fluidized-bed apparatus, as shown in FIG. 20, is known as a device for allowing mixing, granulation, coating, drying or reaction of powder particles by causing a gaseous body such as various gases or air to flow in to the inside of a treatment chamber.
This fluidized-bed apparatus is formed of a truncated cone-shaped container 2A having a dispersion plate 3A (for example, a punched porous plate) for ventilation arranged at the bottom. When this apparatus is used to dry powder particles, heated air is made to flow in to the container 2A from below the dispersion plate 3A, and powder particles 1A put inside the container 2A are dried while being subjected to suspension fluidization.
On the other hand, when using this apparatus for granulation processing, a specified binder fluid (liquid) for granulation (for example, a solution such as carboxymethylcellulose, polyvinyl alcohol, or hydroxypropyl cellulose) is sprayed from a nozzle 4A to powder particles being fluidized to granulate by forming solid bridges between particles by allowing drying of the powder particles at the same time as wet curing.
Recently, in fields such as medical supplies, agricultural chemicals, fertilizers, foodstuff, ceramics etc., there has been a demand to increase the functionality possessed by particles, and to endow particles with new functions in order to manufacture high quality products. There has therefore also been a demand, in the granulation process, for processing of fine powder particles of raw material in the micron and sub-micron order. Specifically, if granulated products of about 50 μm are to be produced, it is necessary to handle fine powder particles of 10-30 μm and also single order micron fine particles as the raw material.
However, since cohesiveness and adhesiveness increase rapidly as particle diameter of the processing material becomes smaller, it is not possible to uniformly fluidize and disperse the powder particles with the previously described existing fluidized bed apparatus. On the other hand, there is a problem that if the amount of heated air supplied is increased in order to achieve uniform fluidization and dispersion, the body of fine powder particles will fly out as it is, handling is extremely difficult, and it is not possible to carry out control to form a satisfactory fluidized bed. Therefore, with the fluidized bed apparatus of the related art, there is a limit to effective fluidized bed control due to the structure of the apparatus itself.
The object of the present invention is to completely solve the above described problems, and to form a fluidized bed controlling behavior of powder particles by introducing gas from outside the treatment chamber via a circumferential faceplate to provide centripetal force to powder particles inside the treatment chamber, and providing centrifugal force on the powder particles in accordance with rotation of the circumferential faceplate. By doing this, it is possible to provide a fluidized bed apparatus for a body of powder particles that can perform various types of processing such as mixing, granulation, coating, drying and reaction even for fine powder particles in the micron or sub-micron range.
In actually realizing such a fluidized bed apparatus, there are various problems to be solved in implementation of the overall structure of the apparatus with taking manufacturability and maneuverability into consideration, such as the specific arrangement and interrelation of various equipment, such as a gas supply device, operation control device, motor, granulation nozzle, operating panel, gas supply piping, wiring etc. as well as maintaining optimization of influx and discharge of gas attributable to size of the treatment chamber and blockage of a bag filter etc.
Another object of the present invention is to solve the problems facing actual making of products described above, and to cause slowing of discharge velocity of gas that has been introduced inside the treatment chamber at an axial region inside the treatment chamber where discharge velocity is high with weak centrifugal force. By doing this, it is possible to efficiently discharge gas that has been introduced into the treatment chamber while balancing centripetal force and centrifugal force on the powder particles regardless of the particle size, and it is possible to carry out optimal operation control of introduction and discharge of gas for fluidized bed behavior. It is also possible to anticipate improved product collection rate by reducing the amount of powder particles sticking to a bag filter accompanying gas flow, and reducing the amount of discharge through the bag filter.
A further object of the present invention to cause gas to flow in to the inside of the treatment chamber in a uniform manner from the entire surface region of gas ventilation means and not excessively circulating gas supplied to gas introduction means, as well as reducing the diameter of a gas supply port, and to enable manufacture of a supply structure without causing a gas supply path to project to the outer surface of a casing. As a result of doing this, arrangement of gas introduction means and a casing and arrangement of the gas introduction means and a treatment chamber, and interrelation between gas introduction means and a gas supply device is optimized, a supply structure for gas in the apparatus overall is simplified, and manufacture of the apparatus becomes simple.